Revision 20:4f843aa9cea1, committed 2015-05-09

Comitter:

XuTianli

Date:

Sat May 09 20:23:19 2015 +0000

Parent:

19:ba8addc061ea

Commit message:

ELEC 2645 Embedded System Project

Changed in this revision

--- a/N5110.cpp	Thu Apr 23 18:57:52 2015 +0000
+++ b/N5110.cpp	Sat May 09 20:23:19 2015 +0000
@@ -6,7 +6,7 @@
 */
 #include "mbed.h"
 #include "N5110.h"
-
+#include "MMA8452.h"
 
 N5110::N5110(PinName pwrPin, PinName scePin, PinName rstPin, PinName dcPin, PinName mosiPin, PinName sclkPin, PinName ledPin)
 {
@@ -404,3 +404,205 @@
     }
 
 }
+
+
+MMA8452:: MMA8452(PinName sdaPin, PinName sclPin)
+{
+    i2c = new I2C(sdaPin,sclPin); // create new I2C instance and initialise
+    i2c->frequency(400000);       // I2C Fast Mode - 400kHz
+    leds = new BusOut(LED4,LED3,LED2,LED1);  // for debug
+}
+
+void MMA8452::init()
+{
+
+    i2c->frequency(400000); // set Fast Mode I2C frequency (5.10 datasheet)
+
+    char data = readByteFromRegister(WHO_AM_I);  // p18 datasheet
+    if (data != 0x2A) { // if correct ID not found, hand and flash error message
+        error();
+    }
+
+    // put into STANDBY while configuring
+    data = readByteFromRegister(CTRL_REG1); // get current value of register
+    data &= ~(1<<0); // clear bit 0 (p37 datasheet)
+    sendByteToRegister(data,CTRL_REG1);
+
+    // Set output data rate, default is 800 Hz, will set to 100 Hz (clear b5, set b4/b3 - p37 datasheet)
+    data = readByteFromRegister(CTRL_REG1);
+    data &= ~(1<<5);
+    data |=  (1<<4);
+    data |=  (1<<3);
+    sendByteToRegister(data,CTRL_REG1);
+
+    //// Can also change default 2g range to 4g or 8g (p22 datasheet)
+    data = readByteFromRegister(XYZ_DATA_CFG);
+    data |=  (1<<0); // set bit 0 - 4g range
+    sendByteToRegister(data,XYZ_DATA_CFG);
+
+    // set ACTIVE
+    data = readByteFromRegister(CTRL_REG1);
+    data |= (1<<0);   // set bit 0 in CTRL_REG1
+    sendByteToRegister(data,CTRL_REG1);
+
+}
+
+// read acceleration data from device
+Acceleration MMA8452::readValues()
+{
+    // acceleration data stored in 6 registers (0x01 to 0x06)
+    // device automatically increments register, so can read 6 bytes starting from OUT_X_MSB
+    char data[6];
+    readBytesFromRegister(OUT_X_MSB,6,data);
+
+    char x_MSB = data[0];  // extract MSB and LSBs for x,y,z values
+    char x_LSB = data[1];
+    char y_MSB = data[2];
+    char y_LSB = data[3];
+    char z_MSB = data[4];
+    char z_LSB = data[5];
+
+    // [0:7] of MSB are 8 MSB of 12-bit value , [7:4] of LSB are 4 LSB's of 12-bit value
+    // need to type-cast as numbers are in signed (2's complement) form (p20 datasheet)
+    int x = (int16_t) (x_MSB << 8) | x_LSB;  // combine bytes
+    x >>= 4;  // are left-aligned, so shift 4 places right to right-align
+    int y = (int16_t) (y_MSB << 8) | y_LSB;
+    y >>= 4;
+    int z = (int16_t) (z_MSB << 8) | z_LSB;
+    z >>= 4;
+
+    // sensitivity is 1024 counts/g in 2g mode (pg 9 datasheet)
+    //  "   "          512      "      4g     "
+    //  "   "          256      "      8g     "
+    Acceleration acc;
+    
+    acc.x = x/512.0;
+    acc.y = y/512.0;
+    acc.z = z/512.0;
+    
+    return acc;
+}
+
+// reads a byte from a specific register
+char MMA8452::readByteFromRegister(char reg)
+{
+    int nack = i2c->write(MMA8452_W_ADDRESS,&reg,1,true);  // send the register address to the slave
+    // true as need to send repeated start condition (5.10.1 datasheet)
+    // http://www.i2c-bus.org/repeated-start-condition/
+    if (nack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    char rx;
+    nack = i2c->read(MMA8452_R_ADDRESS,&rx,1);  // read a byte from the register and store in buffer
+    if (nack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    return rx;
+}
+
+// reads a series of bytes, starting from a specific register
+void MMA8452::readBytesFromRegister(char reg,int numberOfBytes,char bytes[])
+{
+
+    int nack = i2c->write(MMA8452_W_ADDRESS,&reg,1,true);  // send the slave write address and the configuration register address
+    // true as need to send repeated start condition (5.10.1 datasheet)
+    // http://www.i2c-bus.org/repeated-start-condition/
+
+    if (nack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+    nack = i2c->read(MMA8452_R_ADDRESS,bytes,numberOfBytes);  // read bytes
+    if (nack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+}
+
+// sends a byte to a specific register
+void MMA8452::sendByteToRegister(char byte,char reg)
+{
+    char data[2];
+    data[0] = reg;
+    data[1] = byte;
+    // send the register address, followed by the data
+    int nack = i2c->write(MMA8452_W_ADDRESS,data,2);
+    if (nack)
+        error();  // if we don't receive acknowledgement, flash error message
+
+}
+
+void MMA8452::error()
+{
+    while(1) {
+        leds->write(15);
+        wait(0.1);
+        leds->write(0);
+        wait(0.1);
+    }
+}
+
+
+
+N5110 lcd(p7,p8,p9,p10,p11,p13,p26);
+MMA8452 mma8452(p28,p27);
+Serial serial(USBTX,USBRX);
+PwmOut buzzer(p21);
+DigitalOut led(p24);
+float frequency = 500;
+
+int main() {
+    Acceleration acceleration; 
+    mma8452.init();
+    lcd.init();
+    
+    while(1)
+    {
+        lcd.printString("Accelerometer",1,0);
+    acceleration = mma8452.readValues();//read value of acceleration
+    char buffer[14]; 
+        int length = sprintf(buffer,"X = %.2f g",acceleration.x); // print formatted data to buffer
+    char buffer2[14]; 
+         length = sprintf(buffer2,"Y = %.2f g",acceleration.y); 
+    char buffer3[14]; 
+         length = sprintf(buffer3,"Z = %.2f g",acceleration.z); 
+    char buffer4[14]; 
+         length = sprintf(buffer4,"X=%.0fdegree",acceleration.x*90); 
+    char buffer5[14]; 
+         length = sprintf(buffer5,"Y=%.0fdegree",acceleration.y*90);
+    
+        if (length <= 14)  // if string will fit on display
+            lcd.printString(buffer,3,1); 
+            lcd.printString(buffer2,3,2);
+            lcd.printString(buffer3,3,3);
+            lcd.printString(buffer4,3,4);
+            lcd.printString(buffer5,3,5);
+            
+        wait(2.0);
+        lcd.clear();
+        if (acceleration.x>=0.8||acceleration.y>=0.8)
+        {
+            buzzer.period(1/frequency);
+            buzzer=0.5;
+           
+        }
+        else
+        {
+            buzzer.period(1/frequency);
+            buzzer=0;
+            }
+        if (acceleration.x<=0.09&&acceleration.x>=-0.09)
+        {
+            led = 1;
+            }
+       else
+       {
+           led = 0;
+           }
+      
+      
+             
+        }     
+    }
+    
+    
+    
+    
\ No newline at end of file